Optical range finder with directed attention

ABSTRACT

An optical range finder for determining the distance comprises a focusing optical member that focuses emitted electromagnetic radiation upon a micro-mirror array. A processor controls the micro-mirror array to direct the focused electromagnetic radiation into a defined radiation pattern consistent with a lower resolution scan over a greater area and a higher resolution scan over a lesser area of interest within the greater area. A transmission optical member focuses the defined radiation pattern toward an object. A reception optical member receives electromagnetic radiation reflected from the object. A detector detects the receipt of the reflected electromagnetic radiation. A timer determines an elapsed time, between transmission of the electromagnetic radiation to the object and receipt of the electromagnetic radiation from the object, to facilitate determination of the distance between the object and the range finder.

This is a continuation of application Ser. No. 10/662,867, filed on Sep.15, 2003.

FIELD OF THE INVENTION

This invention relates to an optical range finder with directedattention.

BACKGROUND OF THE INVENTION

A range finder means an instrument or device used to determine thedistance of an object from a reference point. In the prior art, a laserrange finder may use a rotating mirror assembly to direct a beamtransmitted from the laser range finder. A laser measurement system ofthe prior art may include a mechanically operated mirror, which scansthrough a certain requisite range of motion to reach a desired settingor angular position. Because such mechanical scanners must typicallyscan through a certain range of motion to reach a desired steering of alaser or light beam, the practical response time of the mechanical laserscanner is greater than desired for certain applications, such asvehicular control. To improve the scan rate of the mechanical scanner, alaser source may be reflected from a multi-sided rotating mirror orprism to produce a broad angular field of view of the laser source overa region. However, the rotating mirror arrangement is costly tomanufacture and susceptible to mechanical failure, such as shock orvibration cracking the mirror or misaligning it.

If the laser range finder is exposed to dust or other particulate matterin an agricultural environment, the range of motion of the laser rangefinder may be impeded and performance may be degraded. Vibration of thelaser range finder may lead to mechanical failure of one or more jointsin a rotating mirror assembly of the prior art laser range finder.Further, the mechanical components of a rotating mirror assembly arelimited to a practical minimum size by manufacturing constraints andcost. The size of the rotating mirror assembly may be too large toaccommodate a desired housing size for a laser range finder.Accordingly, a need exists for a laser range finder with one or more ofthe following characteristics: rapid or real-time responsivenesssuitable for dynamic vehicular control, a compact housing, resistance todust and other particulate matter, and reliability despite exposure tovibration.

SUMMARY OF THE INVENTION

An optical range finder for determining the distance of an object maycomprise an optical source of electromagnetic radiation. A focusingoptical member focuses the electromagnetic radiation upon a micro-mirrorarray. A data processor controls the micro-mirror array to direct thefocused electromagnetic radiation in a defined direction or a definedradiation pattern. A beam adjuster determines a transmitted beam size(e.g., beam width) of the defined radiation pattern in a spatial regionof interest to provide a desired level of resolution for that spatialregion. A transmission optical member focuses the defined radiationpattern toward an object. A reception optical member receiveselectromagnetic radiation reflected from the object or within a field ofinterest. A detector detects the receipt of the reflectedelectromagnetic radiation. A timer determines an elapsed time betweentransmission of the electromagnetic radiation to the object and receiptof the electromagnetic radiation from any object within the field ofview that is sufficiently reflective and of adequate minimal size toprovide return electromagnetic radiation of sufficient strength. A dataprocessor converts the elapsed time into a distance between the objectand a reference point.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one embodiment of an optical range finderfor estimating or determining a distance of an object from a referencepoint.

FIG. 2 is a method for determining a distance or range of an object froma reference point.

FIG. 3 is a block diagram of another embodiment of an optical rangefinder for estimating or determining a distance of an object from areference point.

FIG. 4 is a method for adjusting the beam size of a defined radiationpattern to enhance resolution of the optical range finder.

FIG. 5 is an illustrative example of a first image pattern detected by arange finder.

FIG. 6 is an illustrative example of a second image pattern detected bya range finder.

FIG. 7 is an alternate embodiment of an optical range finder.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a block diagram of an optical range finder 99 fordetermining the distance of an object 108 from a reference point. Thereference point may be defined with reference to the range finder 99 ora portion thereof. The optical range finder 99 comprises an outboundoptical path 101 and an inbound optical path 103. The outbound opticalpath 101 is associated with an electromagnetic signal (e.g., a pulse orpulse train) transmitted from the range finder 99 toward an object 108,whereas the inbound optical path 103 is associated with the reflectedelectromagnetic signal received by the range finder 99. The outboundoptical path 101 comprises an electromagnetic energy source 100, afocusing optical member 102, a micro-mirror array 104, and atransmission optical member 106. The inbound optical path 103 comprisesa reception optical member 110 and a detector 112.

The optical range finder 99 comprises an electromagnetic energy source100 (e.g., a laser) that emits electromagnetic radiation toward afocusing optical member 102 (e.g., a lens). The electromagneticradiation may be an infrared beam, near infra-red, ultraviolet, redlight, a visual spectrum beam or another light beam.

The focusing optical member 102 focuses the electromagnetic radiationupon a micro-mirror array 104. The focusing member 102 may expand thebeam or form the beam into a linear beam. A data processor 116 controlsthe micro-mirror array 104 to direct the focused electromagneticradiation (e.g., linear beam) in a defined direction or a definedradiation pattern. A transmission optical member 106 focuses the definedradiation pattern toward an object 108.

A reception optical member 110 is arranged to receive electromagneticradiation reflected from the object 108. A detector 112 detects thereceipt of the reflected electromagnetic radiation. The receipt of thereflected radiation pattern is associated with a reception time. Forexample, the detector 112 generates a detection signal proportional tothe intensity of the received beam reflection. A timer 118 determines anelapsed time between a transmission time of a transmission of theelectromagnetic radiation (e.g., an identifiable or traceable pulse) tothe object 108 and a reception time of the receipt of theelectromagnetic radiation (e.g., an identifiable or traceable pulse)from the object 108. The elapsed time between when the beam leaves thefinder 99 and when it returns to the finder 99 is used to determine thedistance between the finder 99 and the object 108. A data processor 116converts the elapsed time into a distance between the object 108 and areference point, such as the range finder. If the beam generatesmultiple returns by striking multiple objects, the elapsed time may beselected as the arrival of the first return, the last return, thestrongest return, an average or median of multiple returns, a mode ofmultiple returns, or as consistent with a suitable, reliable propagationmodel or other statistical model. The distance (D) in meters to theobject 108 or another point of the reflection is equal to the elapsedtime (T) in seconds, divided by two and multiplied by the speed of light(C) in meters per second. That is, D=TC/2.

In one embodiment, the electromagnetic energy source 100 transmits oneor more pulses (e.g., identifiable or traceable pulse) ofelectromagnetic radiation and a timer 118 registers a transmission time.In another embodiment, the electromagnetic energy source 100 may outputvarious frequencies or frequency ranges of visible light to facilitatedetermination of the color of an object 108 based on the presence orabsence of reflected energy from the object with respect to transmittedfrequency from the finder. In yet another embodiment, theelectromagnetic energy source 100 comprises a laser with an output powerthat is considered safe for human exposure in accordance with applicabletechnical and or regulatory standards (e.g., U.S. and internationalstandards; Federal Communication Commission rules or regulations).

In one embodiment, the micro-mirror array 104 comprises amicro-electromechanical device that supports the output of a randomlyaccessible beam position or alignment and a variable beam size. Forexample, a micro-mirror array may comprise a micro-electromechanicalsystem (MEMS), a compliant micro-electromechanical system (CMEMS) oranother device.

The micro-mirror array 104 comprises arrays of reflective members (e.g.,mirrors) associated with a substrate (e.g., a semiconductor substrate).Reflective members may be energized individually, collectively, or insequence, or any combination of the foregoing, to scan over a desiredarea (e.g., field of view). Each reflective member may be energized viaone or more capacitive plates or conductive members to deform, andhence, steer the reflective member to direct the electromagneticradiation (e.g., light beam). More than one reflective member mayreflect the electromagnetic radiation (e.g., the light beam) at onetime, resulting in a larger beam than if just a single reflective memberreflected the electromagnetic radiation (e.g., beam).

A beam adjuster 117 controls the micro-mirror array 104 to have acontrolled radiation pattern. For example, the controlled radiationpattern comprises at least one of the following: first pattern forscanning a field of view, a second pattern for covering a sample of thefield of view, and a third pattern for covering a sub-area of the fieldof view. The beam adjuster 117 determines a beam width or beam size ofthe defined radiation pattern. Accordingly, the output beam size,intensity or both may be dynamically adjusted for scanning an area ofinterest (e.g., a global area of interest or local area of interest).Further, the range finder 99 can provide fine tuning of a scan path(e.g., a scan line) or greater resolution scan path by changing afraction of the asserted reflective members comprising the beam. Thebeam adjuster 117 can adjust the beam dynamically without any limitationfrom the rotation rate of a multi-sided mechanical mirror of prior artsystems.

In one embodiment, elastomers are added between the reflective memberand the substrate of the micro-mirror array 104 to decrease the responsetime from deformation to rest after the energy is removed from a member.The elastomer associated with the reflective elements may be used toimprove the range of motion of the reflective elements, which in turn,improves the angular scan range. The elastomer associated with thereflective elements may lower the energy or voltage needed to controlthe micro-mirror array 104. Micromirror arrays 104 may be fabricated bysemiconductor and integrated circuit fabrication techniques. Features ofmicro-mirror arrays may be constructed of one or more of the following:silicon, silicon oxide, silicon nitride, aluminum, silver, and nickel.

The tilt or movement of the reflective members are controlled byelectrostatic charges applied to electrodes. Semiconductor switches,such as complementary metal oxide semiconductor (CMOS) transistors, maybe used to control the position of the reflective members byelectrostatic deflection and sense the position of the reflectivemembers by capacitive sensing. The capacitive sensing of the position ofthe reflective members provides feedback for fine-tuning of thepreferential alignment of the reflective members and electrical energyrequired to attain such alignment. The beam adjuster 117 may acceptinput from capacitive sensing and may operate semiconductor switches ora driver to control the electrostatic charges applied to the electrodes.

The micro-mirror array 104 supports activation of different reflectiveelements in virtually any sequence (e.g., a random sequence) to achievea desired position of the reflective elements, rather than scanningthrough in a particular sequence of motion to reach a desired positionor angular title of a mirror, as might be required with mechanical laserscanners. Accordingly, the micro-mirror array 104 supports dynamic,“random access” to mirror positioning for structured light. Themicro-mirror array 104 may provide data on a region or area of interestin terms of coordinates, intensity, and distance.

A driver may be interposed between the beam adjuster 117 and themicro-mirror array 104 to provide an electronic interface between thebeam adjuster 117 and micro-mirror array 104. The beam adjuster 117 mayestablish a scanning pattern or energization pattern for applyingelectrical energy to one or more selected reflective elements of themicro-mirror array 104. For example, a micro-mirror array 104 may beenergized to project a linear arrangement of pixels or other patterns ofstructured light. The driver or beam adjuster may activate eachsuccessive member of the micro-mirror array 104 prior to the time themember is actually required to minimize the delay associated withactivating and moving the member of the micro-mirror array 104. That is,the temporal offset between energy activation of successive members isminimized, which reduces the response time of the micro-mirror array104. The micro-mirror array 104 provides random access to mirrorpositioning to produce fixed structured light.

The beam adjuster 117 energizes the micro-mirror array 104 to providepulses of light or emissions, where time of flight is measured from areflective obstacle or another object 108. The micro-mirror array 104supports great flexibility and efficiency in image data collection. Forexample, a first beam with a lower resolution gathers a smaller set ofscanned image data points (e.g., first scan data) than a second beamwith a greater resolution. The reflection received by reception of theoptical member 110 from the first beam can be used to identify whereobjects 108 of potential interest lie. The reflection received by thereception of the optical member 110 from a second beam at higher scanresolution can then be used to gather high density data limited to thelocal regions of interest. There can be significant data collectionefficiency improvements (e.g., time saving) by doing the courseresolution scan of the first beam followed by a high resolution scan ofthe second beam, rather than taking high resolution scan of the wholescene and then processing the voluminous data from the high resolutionscan of the whole scene (e.g., global area of interest) to extractinformation in the areas of interest. In one embodiment, the whole scenerepresents a crop edge and the local area of interest represents a gapor break in the crop edge (e.g., from stunted plant growth or apreviously harvested area). Here, the local region of interest isidentified by one or more discontinuities in the reflectivity of thewhole scene or crop edge or discontinuities with respect to certainfrequencies of transmitted light.

FIG. 2 is a flow chart of a method for determining a distance of anobject 108 from a reference point. The method of FIG. 2 begins in stepS200.

In step S200, an electromagnetic energy source 100 emits electromagneticradiation (e.g., a light beam). A timer 118 may record the timeassociated with the transmission of an identifiable pulse ofelectromagnetic radiation from the range finder 99.

In step S202, a focusing optical member 102 focuses the electromagneticradiation upon a micro-mirror array 104. In one example, a lens, as thefocusing optical member 102, may focus the electromagnetic radiationupon the micro-mirror array 104. In another example, a diffractiongrating, as the optical member, focuses the electromagnetic energy uponthe micro-mirror array 104.

In step S204, the micro-mirror array 104 directs the focusedelectromagnetic radiation in a defined direction or defined radiationpattern toward an object 108 (e.g., a plant, obstacle, crop, crop edgeor stubble), consistent with a lower resolution scan over a greater areaor a higher resolution scan over a lesser area of interest based on aprevious lower resolution scan over the greater area.

In step S206, the transmission optical member 106 focuses the definedradiation pattern toward an object 108. For example, a transmissionlens, as a transmission optical member 106, focuses the definedradiation pattern.

In step S208, a reception optical member 110 is arranged to receiveelectromagnetic radiation (e.g., a light beam) reflected from the object108, if the object is of sufficient physical size and reflectivity. Forexample, a reception lens, as the reception optical member 110; receiveselectromagnetic radiation reflected from the object 108 and focuses thereceived electromagnetic radiation on a detector 112. In oneillustrative example, the received electromagnetic radiation may befiltered or applied to a filter prior to striking the detector 112 toreject or pass certain frequencies of the electromagnetic radiationreceived. Filtering may be used to detect the presence of objects 108having certain colors.

In step S210, a detector 112 detects the receipt of the reflected,received electromagnetic radiation. The electromagnetic radiation may bereflected from the object. For example, the detector 112 may represent acharge-coupled device, an cadmium sulfide sensor, a complementary metaloxide semiconductor or another sensor that emits an electrical signalwhen electromagnetic energy, such as light, is incident upon the sensor.The electrical signal emitted may be used to determine a time of arrivalor reception time associated with an identifiable pulse. The timer 118may record a reception time or a time of arrival associated with thereception of an identifiable pulse or modulated signal ofelectromagnetic radiation. The transmission time and reception time ofthe identifiable pulse or modulated signal may be measured with respectto each other or a reference time frame

In step S212, a data processor 116 determines an elapsed time between atransmission time of the electromagnetic radiation to the object 108 anda reception time of receipt of the electromagnetic radiation from theobject 108.

In step S214, a data processor 116 or a converter 114 converts theelapsed time into a distance between the object 108 and the referencepoint. The distance between the object 108 and the reference point maybe used as an input to a guidance system of a work vehicle. Workvehicles include, but are not limited to, agricultural machines such ascombines, harvesters, and tractors; construction equipment; forestryequipment, such as harvesters and forwards; and turf care equipment,such as mowers; and off-road utility vehicles. The distance may bedetermined in accordance with the following equation: D=TC/2, where D isthe distance in meters to the object, T is the elapsed time in secondsdivided by two and multiplied by the speed of light C in meters persecond.

FIG. 3 is a block diagram of an alternate embodiment of a range finder.The range finder 101 of FIG. 3 is similar to the range finder 99 of FIG.1, except the range finder 101 of FIG. 3 further includes a transmissionfilter 120 and a reception filter 122. Like elements in FIG. 1 and FIG.3 indicate like elements.

The optical range finder 101 comprises an outbound optical path 105 andan inbound optical path 107. The outbound optical path 105 is associatedwith an electromagnetic signal (e.g., a pulse or pulse train)transmitted from the range finder 101 toward an object 108, whereas theinbound optical path 107 is associated with the reflectedelectromagnetic signal received by the range finder 101. The outboundoptical path 105 comprises an electromagnetic energy source 100, afocusing optical member 102, a transmission filter 120, a micro-mirrorarray 104, and a transmission optical member 106. The inbound opticalpath 107 comprises a reception optical member 110, a reception filter122, and a detector 112.

In one embodiment, the transmission filter 120 comprises an intensityfilter. For example, the intensity filter may represent a liquid crystaldisplay or a rotatable disk with various selectable levels oftransparency. The transmission filter may attenuate the transmittedelectromagnetic radiation to maintain eye-safe output levels of thetransmitted electromagnetic radiation from the outbound optical path.The intensity filter may attenuate the transmitted electromagneticradiation from the electromagnetic energy source 100 to limit themaximum distance from which a return signal may be detected.Accordingly, the intensity filter may be used to automatically filterout objects 108 from outside a certain range of interest. It would alsoallow the scanning rate to be increased, since the time per acquireddata point is limited by the maximum mean round-trip time to the mostdistance object 108 that may generate a return. The transmission filter120 might also be placed between the micro-mirror array 104 and thetransmission optical member 106, but in the location shown, themicro-mirror array 104 is saved from extra heat from the fullelectromagnetic radiation generated by the source incident on it.

In another embodiment, the transmission filter 120 comprises afrequency-selective filter for passing or rejecting a particularfrequency of electromagnetic radiation. For example, the filter 120 maybe configured to block or pass green light, red light or blue light orother colors. By changing from one filter 120 to another with adifferent frequency response and detecting the amplitude of thereflected signals, the data processor can estimate an approximate colorof an object 108.

FIG. 4 is a flow chart of a method of determining whether to use a highresolution scan or a low resolution scan. The method of FIG. 4 may beapplied to carry out step S204 of FIG. 2. The method of FIG. 4 begins instep S400.

In step S400, a greater area of interest is scanned at a lowerresolution level to obtain first scan data. The first scan data mayinclude background data, foreground data, or both. The data processormay not have adequate information available from the first scan data tocompletely discriminate between background data and foreground data inthe first scan data. A foreground object is located in front of abackground object and is closer to the range finder (e.g., 99 or 101).

In step S402, a local region of interest is determined within thegreater area based on the first scan data. The first scan data maydetect one or more objects (e.g., 108) or potential objects at multipledistances in a global scan region. To ascertain or verify the presenceand location of objects, the transmitted beam size (e.g., width) isreduced to a smaller beam size.

In one embodiment, the local region of interest represents one or moreregions where foreground objects were potentially detected. In oneexample, the directed attention of this invention is particularlywell-suited for the forest domain where trees as the background objectsmay need to be detected through the foreground brush. The foregroundbrush may represent one or more foreground objects.

If no foreground object is present or potentially present, the localregion of interest may represent a portion of the background object or adiscontinuity region between one or more background objects. Adiscontinuity may represent a material change in the amplitude of thereceived electromagnetic radiation or reflection. Further, thediscontinuity may represent a change in amplitude for a particularfrequency (e.g., green light) or frequency band of the receivedelectromagnetic radiation. For example, a global area of interestrepresents a crop edge and a discontinuity therein represents a localarea of interest. The crop edge may reflect a first frequency of light,whereas a discontinuity does not reflect the first frequency of light orreflects a second frequency of light, distinct from the first frequency.

In step S404, a local area of interest is scanned at a higher resolutionlevel to obtain second scan data (e.g., foreground data). For example,the data processor 116 or beam adjuster 117 may direct the attention ofthe beam via a higher resolution scan with a narrower beam size (e.g.,over a local area of interest), based on the return signal from a widerbeam pulse or modulated signal of the first scan. If the environmentpermits, the second scan or higher resolution scan supportsdistinguishing background objects from foreground objects of lesserphysical size than that lower resolution scan does. In addition, thehigher resolution supports separating objects based on the higherresolution.

Step S404 may be carried out in a variety of ways. For example, the beamadjuster 117 may automatically reduce the beam size by selectiveenergization of the micro-mirror array 104 to focus the transmittedelectromagnetic beam from the range finder 101 over a global area ofinterest or a local area of interest at the higher resolution. Themicro-mirror array 104 supports random access scanning and on-the-flybeam size adjustment transmitted from the range finder (e.g., 99 or101). The resolution adjustment supports first scanning an entire globalregion at a lower resolution and secondly scanning a local region ofinterest at a higher resolution. No mechanical lens adjustment isrequired and no alignment of the rotating mirrors through a completemovement range is required as in the prior art.

In step S406, the first scan data is integrated with the second scandata to provide a two or three-dimensional map of the greater area ofinterest to facilitate identification of at least one of an obstacle, alandmark or guidance context. The two or three-dimensional map may beused to construct a path plan for a vehicle (e.g., an autonomous orunmanned vehicle).

In FIG. 4, the decision of whether to use a narrower beam with greaterresolution versus a larger beam with lesser resolution may depend uponwhether or not the greater resolution provides any extra information. Ifthe narrower beam were used at all times, the amount of data collectedwould increase. In turn, the data processing and storage capacityassociated with the data processor 16 would need to be configured tosupport the quantity of the collected data. The time to obtain data fromthe global field of interest would also increase because the collecteddata would likely pertain to other areas outside of the local field ofinterest.

FIG. 5 represents an illustration of first scan data, whereas FIG. 6represents an illustration of second scan data. The first scan data mayrepresent image data in a rectangular region (e.g., 9 inches by 9 inchesin the real world), expressed in columns and rows. The first scan datamay be captured by a larger beam size (e.g., 3 inches by 3 inches),whereas the second scan data may be captured by a smaller beam size(e.g., 1 inch by 1 inch). As illustrated in FIG. 5, the first scan datacontains a large background object and one or more small foregroundobjects within a global region of interest. For example, the largebackground object may comprise a tree trunk, whereas the foregroundobjects may comprise one or more leaves.

The rectangular region of the first scan data of FIG. 5 may be dividedinto a grid or a cellular arrangement with elements identified by rowand column coordinates. As illustrated, there are nine rows and ninecolumns, although in practice, virtually any number of rows and columnscould be present. Suppose that there are leaves (L) with coordinates andranges, respectively, as follows: (column two, row two) at approximately20 feet from the range finder; (column four, row four) at approximately20.3 feet from the range finder, which occludes the tree trunk; and(column seven, row seven) at approximately 20.6 feet from the rangefinder. Further, there is a tree trunk (T) at columns 4-6 atapproximately 21 feet from the range finder. Each of the leaves or trunkportions shown in FIG. 5 is of sufficient physical size and reflectivityto provide enough reflectance to register a sufficient return signal bythe range finder to indicate the presence of an object.

Initially in one illustrative example, the data processor 116 or thebeam adjuster 117 of the range finder (99 or 101) is set on a large beamsize (e.g., a rectangular 9 inch beam) or a low resolution mode for ageneral region of interest at approximately 20 to 21 feet from the rangefinder. In the lower resolution mode, the range finder may provide afirst return of a leaf at row 2, column 2, at approximately 20 feet, thelast return from the trunk at approximately 21 feet or both. The smallforeground objects in front of the trunk may not be recognized by therange finder. Further, the range finder may not be able to distinguishbetween the small foreground object and the background object.

FIG. 6 represents the case where the background object or a portionthereof is identified within a local field of interest. The local fieldof interest of FIG. 6 represents one box or one row-column combinationin FIG. 6. There are nine potential local fields of interest of FIG. 9,which may be selected from three rows and three columns, althoughvirtually any number of rows and columns may be used. The range findermay be set on a smaller beam width (e.g., rectangular 1 inch by 1 inch)with a higher resolution to obtain the second scan data in the localfield of interest. The return signal is resolved on a time-of-flighttime basis so that within the smaller beam width or higher resolution,objects are detected at approximately 20 feet from the range finder, atapproximately 20.3 feet from the range finder, 20.6 feet from the rangefinder, and 21 feet from the range finder. Leaves are detected in columnone, row one, column two, row two, and column three, row three. The treetrunk is detected in column two, rows one through three, inclusive.

FIG. 7 illustrates an alternate embodiment of the range finder 199. Therange finder of FIG. 7 is similar to the range finder 99 of FIG. 1,except the range finder 199 of FIG. 7 further includes an optical camera171. The optical camera 171 may be used to identify regions of likecolor that may correspond to surfaces at given distances. Although acolor camera may provide an output of a color signal, which includes ared component, a green component, and a blue component, in an alternateembodiment the color camera may provide a near infra-red component orsignal instead of, or in addition to, the red component, the greencomponent and the blue component. The color signal may provide anintensity value of pixels or groups of pixels for each corresponding redcomponent, green component, and blue component for the area scanned. Inthe example above, suppose that the leaves are green, the trunk isbrown, and background is sky blue. If the optical camera 171 and laserbeam were calibrated and coordinated, the processing of the camera imageby the data processor 119 would show two blue regions on each side ofthe trunk, three green regions where the leaves were, and the brownregion where the trunk is. These regions identified in the camera imagecould be used as first guesses of where the multiple ranges in thelarger rectangular beam width could be resolved.

Having described the preferred embodiment, it will become apparent thatvarious modifications can be made without departing from the scope ofthe invention as defined in the accompanying claims.

1. An optical device for measuring a distance between the optical deviceand an object, the optical device comprising: an optical source foremitting a beam of electromagnetic radiation; a focusing optical memberfor focusing the beam of electromagnetic radiation into a micro-mirrorincident pattern; a micro-mirror array receiving the micro-mirrorincident pattern and outputting a controlled radiation pattern; aprocessor for selecting a resolution level of the controlled radiationpattern of narrower beam size based on a previous lower resolution scanof greater beam size over a greater area; a beam adjuster forselectively energizing one or more selected elements of the micro-mirrorarray to reduce a beam size of the beam from the greater beam size tothe narrower beam size; and a transmission optical member for focusingthe controlled radiation pattern toward an object for estimation of adistance of the object from the optical device.
 2. The optical deviceaccording to claim 1 wherein the micro-mirror array comprises amicroelectromechanical system.
 3. The optical device according to claim1 wherein the micro-mirror array comprises an array of deformablereflective members and a controller for controlling the deformablereflective members to direct the controlled radiation pattern.
 4. Theoptical device according to claim 1 wherein the beam adjuster activatessuccessive members of the micro-mirror array prior to the time that achange in the position of the member is actually required to reduce aresponse time of the micro-mirror array.
 5. The optical device accordingto claim 1 wherein the controlled radiation pattern has a beam sizedetermined by reflective contributions from multiple reflective membersof the micro-mirror array.
 6. The optical device according to claim 1wherein the controlled radiation pattern comprises a first beam with alower resolution and a second beam with a higher resolution, the firstbeam providing first scan data to identify a local area of interestwithin a global area, the second beam providing second scan dataassociated with the local area of interest.
 7. The optical deviceaccording to claim 1 wherein the optical source comprises a laser, thefocusing optical member comprises a lens, and the transmission opticalmember comprises a lens.
 8. The optical device according to claim 1further comprising an intensity filter intercepting a path of thecontrolled radiation pattern for limiting the maximum distance of atleast one of a global area of interest and a local area of interest. 9.The optical device according to claim 1 further comprising at least onefrequency-selective filter intercepting a path of a reflection of thecontrolled radiation pattern from the object for filtering a reflectedradiation pattern from the object to estimate an approximate color ofthe object.
 10. The optical device according to claim 1 wherein a firstscan is directed to a background object and a potential foregroundobject and wherein a second scan is directed at the potential foregroundobject to verify the presence or absence of the potential foregroundobject.
 11. The optical device according to claim 1 wherein a first scandata is directed to a global region of interest and a second scan isdirected to a local region of interest, the local region of interestrepresenting a discontinuity associated with an object, a discontinuityrepresenting a material change in the an amplitude of a reflection ofthe controlled radiation pattern from the object or an absence of thereflection within a predefined vicinity of the object.
 12. The opticaldevice according to claim 11 wherein the discontinuity represents abreak or interruption in a crop edge of a field.
 13. The optical deviceaccording to claim 1 wherein a color camera is used to identify regionsof like color that may correspond to surfaces of the object at givendistances.
 14. The optical device according to claim 1 furthercomprising a lens for collecting a reflection of the controlledradiation pattern from the object; a detector for receiving thereflection and providing an output signal to the processor; and a timerassociated with the processor for determining an elapsed time betweentransmission of an identifiable pulse of electromagnetic radiation fromthe source and the reception of the reflection of the identifiable pulseat the sensor, the elapsed time indicative of a distance between theoptical device and the object.
 15. The optical device according to claim14 wherein a filter is interposed between the lens and the sensor, thefilter adapted to filter or reject at least one frequency of reflectedelectromagnetic radiation associated with the object.
 16. An opticalsystem for determining the range of an object, the optical systemcomprising: an optical source of electromagnetic radiation, a firsttransmitting lens for focusing or collimating the electromagneticradiation; a micro-mirror array for directing the focusedelectromagnetic radiation in a defined direction or pattern, a secondtransmitting lens for focusing the electromagnetic radiation reflectedfrom the micro-mirror array; a processor arranged to control themicro-mirror array to direct the focused radiation in the defineddirection or pattern toward an object, the focused radiation having aresolution selected between a lower resolution scan of greater beam sizeover a greater area or a higher resolution scan of narrower beam sizeover a lesser area of interest based on a previous lower resolution scanover the greater area; a beam adjuster for selectively energizing one ormore selected elements of the micro-mirror array to reduce a beam sizeof the pattern from the greater beam size to the narrower beam size; areceiving lens for receiving electromagnetic radiation reflected fromthe object, a detector for detecting the receipt of the reflectedelectromagnetic radiation; a timer for determining an elapsed timebetween transmission of the electromagnetic radiation to the object andreceipt of the electromagnetic radiation from the object; and aconverter for converting the elapsed time into a distance between theobject and the optical system.
 17. A method for determining a distanceof an object from a reference point, the method comprising: emittingelectromagnetic radiation; focusing the electromagnetic radiation upon amicro-mirror array; directing the focused electromagnetic radiation in adefined direction or defined radiation pattern toward an object,consistent with a lower resolution scan of greater beam size over agreater area or a higher resolution scan of narrower beam size over alesser area of interest based on a previous lower resolution scan overthe greater area; energizing one or more selected elements of themicro-mirror array to reduce a beam size of the pattern from the greaterbeam size to the narrower beam size; receiving electromagnetic radiationreflected from the object; detecting the receipt of the reflectedelectromagnetic radiation; determining an elapsed time betweentransmission of the electromagnetic radiation to the object and receiptof the electromagnetic radiation from the object; and converting theelapsed time into a distance between the object and the reference point.18. The method according to claim 17 further comprising: filtering theemitted electromagnetic radiation received to control the intensityrange of the focused electromagnetic radiation upon the micro-mirrorarray.
 19. The method according to claim 17 further comprising:filtering the reflected electromagnetic radiation received to controlthe intensity range of incident electromagnetic radiation upon thedetector.
 20. The method according to claim 17 further comprising:filtering the reflected electromagnetic radiation from an object in afrequency-selective manner to estimate an approximate color of theobject.
 21. The method according to claim 17 further comprising:directing the lower resolution scan to a background object and apotential foreground object; directing the higher resolution scan at thepotential foreground object to verify the presence or absence of thepotential foreground object at a particular spatial position.
 22. Themethod according to claim 17 further comprising: directing the higherresolution scan to a global region of interest; directing the higherresolution scan to the local region of interest representing adiscontinuity associated with an object, a discontinuity representing amaterial change in an amplitude of a reflection of the controlledradiation pattern from the object or an absence of the reflection withina predefined vicinity of the object.
 23. The method according to claim22 wherein the discontinuity represents a break or interruption in acrop edge of a field.
 24. The method according to claim 17 furthercomprising identifying regions of like color that may correspond tosurfaces of the object at given distances.
 25. The method according toclaim 17 further comprising: scanning for the lower resolution scan anda second beam for the higher resolution scan, the first beam providingfirst scan data to identify a local area of interest within a globalarea of interest, the second beam providing second scan data associatedwith the local area of interest.
 26. The method according to claim 17further comprising: processing at least one of a red component, a greencomponent, a blue component, and a near infrared component to determinea color of the object.